Method and apparatus for heating solutions within intravenous lines to desired temperatures during infusion

ABSTRACT

An IV line temperature controlled warming device includes a housing and a fluid cassette or cartridge that receives fluid from an IV line and includes intravenous line tubing arranged in a preformed configuration. The configuration includes tubing sections arranged in generally circular and concentric portions and a central serpentine tubing section that basically reverses fluid flow and facilitates flow in opposing directions within adjacent tubing sections. The fluid cassette is retained within the device on a base plate partially disposed within a device housing interior, while a housing cover is selectively opened and closed to permit access to the base plate. The base plate includes a heater plate disposed thereon, while the cover and heater plate each include heating elements to apply heat to opposing surfaces of the tubing cassette. The heating elements are controlled by a controller in response to measured temperatures of the heater plate and fluid.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention pertains to devices for warming intravenous (IV)solution during infusion into a patient. In particular, the presentinvention pertains to a device for receiving and heating a preformed IVtubing cassette or cartridge connected to an IV line to warm solutionflowing within the line to a desired temperature during infusion into apatient.

2. Discussion of Related Art

Intravenous (IV) fluids are typically infused into a patient utilizing aliquid filled bag or container and an IV fluid line. The fluids aregenerally delivered from the container to the patient via gravitationalforces and/or applied pressure. It is important in many situations thatthe temperature of the fluid within the IV line be maintained within adesirable and safe temperature range upon entering the patient body soas to eliminate any potential for thermal shock and injury to thepatient.

Accordingly, the related art provides several devices for controllingthe temperature of fluid in an IV line for infusion into a patient. Forexample, U.S. Pat. No. 4,167,663 (Granzow, Jr. et al.) discloses a bloodwarming device including a housing with a heating compartment and anaccess door. The heating compartment includes a warming bag that isinternally baffled to define a tortuous flow path and has an inlet portand an outlet port for allowing fluid to flow through the bag. The bagis sandwiched between a plate on the access door and an opposing platewithin the heating compartment. The two plates include heating elementsto heat the bag and the fluid flowing therein. The device furtherincludes temperature sensors to measure the temperature of fluid flowingwithin the bag and control circuitry to control the heating elements inaccordance with the measured temperatures.

U.S. Pat. No. 4,356,383 (Dahlberg et al.) discloses a fluid heatingapparatus including a box-shaped member having an enclosure member orcap, a conduit or bag disposed between the box-shaped member and cap anda pair of heating plates respectively connected to the box-shaped memberand cap to abut opposing sides of the conduit and heat fluid flowingtherethrough. A temperature sensing device is positioned for engagingthe conduit at a predetermined location to sense the temperature offluid within the conduit. The apparatus further includes a contactmember to engage the conduit at a predetermined location for compressingthe conduit to constrict the cross-sectional area of the flow passagewhen the flow rate of fluid is below a predetermined flow rate.

U.S. Pat. No. 5,245,693 (Ford et al.) discloses an apparatus for heatingparenteral fluids for intravenous delivery to a patient. The apparatusincludes a disposable cassette which is made up of a unitary memberdivided to form a serpentine flow path by a plurality of pathseparators. Thin, flexible metallic foil membranes are sealingly joinedto the unitary member on the upper and bottom surfaces thereof to forman enclosed, fluid-tight serpentine flow path between the plurality ofpath separators. The entire periphery of the unitary member and heatconductive foil membranes are sealingly held by a framework. Thedisposable cassette slides between first and second heating blocks whichcontact the heat conductive foil membranes so as to provide heattransfer to fluid flowing in the serpentine flow path. The heatingblocks are designed to provide a gradation of heat energy where moreheat is energy is available for transfer to the fluid at the inlet endof the serpentine flow path than that available for transfer to thefluid at the serpentine flow path outlet end.

U.S. Pat. No. 5,381,510 (Ford et al.) discloses a disposable, in-lineheating cassette and apparatus for raising the temperature of fluids.The cassette comprises a spacer defining a sinuous or serpentine flowpathway interposed between flexible foils and mounted on a frame. Theframe comprises inlet and outlet tubes and related input and outputparts which communicate with the serpentine path. Juxtaposed heatingplates in direct contact with the cassette substantially contact theentire heating surface of the foils, thereby providing a thermal pathfrom the heating plate to the foil and further to the fluid. The heatingplates have several electrically conductive strips thereon forgenerating a gradation of heat energy where more heat energy isavailable for transfer at the inlet end than at the outlet end of theserpentine flow path.

U.S. Pat. No. 6,175,688 (Cassidy et al.) discloses an intravenous fluidheater dimensioned to be wearable adjacent a patient intravenous fluidinfusion situs. The heater includes a heat exchanger for defining a flowpath through the heater for fluid to be infused via the infusion situs.At least one controllable heating element is provided for heating thefluid in the flow path by heat conduction thereto through the heatexchanger. Sensors are included for sensing respective temperatures ofentering and exiting fluids of the flow path. A controller controlsheating of the fluid in the flow path based on temperatures of theexiting fluids to cause the fluid in the flow path to be substantiallyuniformly heated to a desired infusion temperature prior to exiting theheater.

U.S. Pat. No. 6,261,261 (Gordon) discloses an infrared heating devicefor prewarming solutions that includes a cassette having a predeterminedlength of tubing connectable between an IV solution source and aninfusion site for a patient. An infrared energy-generating sheet ispositioned onto the cassette adjacent the IV tubing. In one embodimentof the device, the IV tubing is arranged in a spiral path on thecassette.

The related art devices described above suffer from severaldisadvantages. In particular, the Granzow, Jr. et al., Dahlberg et al.,Ford et al. and Cassidy et al. devices each generally employ housingsthat inhibit viewing of fluid during treatment. Thus, the fluid mayincur certain undesirable conditions within the devices (e.g.,contamination, air bubbles, etc.) that are beyond the view of, and maybe undetected by, an operator, thereby risking serious injury to apatient. Further, these devices tend to employ heat exchangers generallywith a serpentine fluid flow path defined therein that typicallyincludes a plurality of overlapping fluid flow passageways. The pathgenerally includes dimensions different than those of the fluid lines,thereby tending to affect the rate of fluid flow and, consequently, theamount of thermal energy required to heat the fluid to a desiredtemperature. As a result, the devices may need to further employ flowsensors to measure and account for changes in fluid flow in order toensure maintenance of proper fluid temperature, thereby increasingsystem complexity and costs. Moreover, the overlapping passageways tendto confine thermal energy that may otherwise be distributed to heat thefluid, thereby limiting the device heating potential. The Gordon deviceutilizes a cassette with a fluid flow path formed of tubing. However,this device employs infrared radiation to thermally treat the fluid,thereby involving special safety measures and requiring additionalcomponents to isolate the radiation from the patient. In addition, theabove-described systems of the related art include heat exchangers orfluid flow paths including inlets separated from fluid outlets, therebytending to increase complexity of connections and installation for usewith an infusion apparatus.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to warm solutionwithin an IV line during infusion by heating a preformed IV tubingcassette or cartridge connected to and receiving solution from the IVline.

It is another object of the present invention to uniformly heat an IVtubing cassette or cartridge containing solution from an IV line bysimultaneously heating opposing cassette surfaces.

Yet another object of the present invention is to disable operation ofan IV solution warming device in response to detecting the absence of acassette within that device.

Still another object of the present invention is to configure an IVtubing cassette or cartridge to occupy a minimal amount of warmingdevice housing space, while providing sufficient residence time forfluid to be heated to a desired temperature within the device.

A further object of the present invention is to thermally treat awarming device IV tubing cassette or cartridge containing fluid, whileenabling viewing of the fluid within the device.

Yet another object of the present invention is to heat IV solution witha warming device employing an IV cassette or cartridge including tubingarranged to form concentric passages that alternately direct IV solutionflow in opposing directions to enhance thermal transfer between thepassages during solution warming.

The aforesaid objects may be achieved individually and/or incombination, and it is not intended that the present invention beconstrued as requiring two or more of the objects to be combined unlessexpressly required by the claims attached hereto.

According to the present invention, an IV line temperature controlledwarming device includes a housing and a fluid cassette or cartridge thatreceives fluid from an IV line and includes intravenous line tubingarranged in a preformed configuration to enable the IV line fluid toflow therethrough. The preformed configuration includes tubing sectionsarranged in generally circular and concentric portions and a centralserpentine tubing section that includes a generally ‘S’-shapedconfiguration. The serpentine section basically reverses fluid flow andfacilitates flow in opposing directions within adjacent tubing sections.The fluid cassette is retained within the device on a base platepartially disposed within a device housing interior, while a housingcover is selectively opened and closed to permit access to the baseplate. The base plate includes a heater plate disposed thereon, whilethe cover and heater plate each include heating elements to apply heatto opposing surfaces of the tubing cassette. The heating elements arecontrolled by a controller in response to measured temperatures of theheater plate and fluid. In addition, the device includes varioussafeguards that ensure device operation during appropriate conditions(e.g., appropriate temperatures, proper placement of a compatiblecassette within the device, etc.).

The above and still further objects, features and advantages of thepresent invention will become apparent upon consideration of thefollowing detailed description of specific embodiments thereof,particularly when taken in conjunction with the accompanying drawings,wherein like reference numerals in the various figures are utilized todesignate like components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in perspective of an IV line temperature controlledwarming device including an IV tubing cassette or cartridge disposedtherein according to the present invention.

FIG. 2 is an exploded view in perspective of the warming device of FIG.1.

FIG. 3 is a view in perspective of a heating element for a cover of thewarming device of FIG. 1.

FIG. 4 is an exploded view in perspective of an outlet tubing portion ofthe cassette of FIG. 1 disposed on a device base plate and including asensor fitting to measure temperature of fluid within the cassette.

FIG. 5 is an electrical schematic diagram of an exemplary controlcircuit for the warming device of FIG. 1.

FIG. 6 is a side view in perspective of a mount utilized to support awarming device according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An IV line temperature controlled warming device for heating andmaintaining fluids flowing within an IV fluid line at desiredtemperatures is illustrated in FIG. 1. Specifically, warming device 2includes a housing 10 with a lid or cover 22 pivotally attached thereto.The warming device receives a tubing cassette or cartridge 50 that istypically connected to an intravenous line (IV) supplying intravenoussolution from an IV solution bag or container to a patient. The devicehousing includes a base plate 30 to receive cassette 50 and a heaterplate 42 disposed on the base plate beneath the cassette to heat acassette bottom surface as described below. An additional heater orheating element 25 is disposed on cover 22 to heat the cassette topsurface as described below. Thus, the cassette is disposed between theheater plate and cover heating elements to receive heat on opposingcassette surfaces for uniform heating of solution or other fluid flowingtherein. A controller 62 is partially disposed within the housing toenable entry of desired solution temperatures and to control deviceoperation as described below. The warming device may be oriented in avariety of positions (e.g., horizontally, vertically, etc.) and may bemounted to or supported by various structures (e.g., a patient arm orother body portion, swing arm, arm board, bed, bed rail, operating roomor other table, IV pole, wall, floor, posts, etc.). The warming deviceis preferably positioned in close proximity to an infusion site of apatient in order to heat IV fluid (e.g., may heat fluid with or withoutskin contact), and may be portable for use in various locations. Thewarming device may be utilized for operating room, pre-op and/or post-opprocedures or at any other times where infusion is being performed. Inaddition, a pre-heated IV solution bag or container may be used inconjunction with the warming device. In this case, the device istypically disposed at or near the patient infusion site and basicallyheats the fluid to compensate for heat loss during infusion due toexposure of the fluid to the ambient environment.

Referring to FIGS. 2-4, housing 10 includes front and rear walls 12, 14,side walls 16, 18 and a bottom wall 20. Side walls 16, 18 are attachedto and extend between front and rear walls 12, 14, while bottom wall 20is attached to the bottom edges of the front, rear and side walls. Thehousing walls are substantially rectangular and collectively define ahousing interior with an open top portion. It is to be understood thatthe terms “top”, “bottom”, “side”, “front”, “rear”, “horizontal”,“vertical”, “upper”, “lower”, “up”, “down”, “height”, “length”, “width”,“depth” and the like are used herein merely to describe points ofreference and do not limit the present invention to any specificorientation or configuration. Front wall 12 includes a substantiallyrectangular opening 13 defined therein for receiving controller 62. Thecontroller is disposed through the front wall and partially within thehousing interior. The housing may be constructed of any suitable rigidmaterial (e.g., plastic), and is preferably constructed of asubstantially transparent material to permit viewing of the fluid withinthe cassette, especially during heating. This enables an operator todetect various conditions (e.g., contamination, air bubbles, etc.) thatmay cause injury to a patient. The housing basically houses the deviceelectrical components and supports the base plate as described below.

Base plate 30 has a generally rectangular configuration and includes alower portion 31 that is suitably dimensioned to fit within the housingopen top portion. The base plate is constructed of a suitably rigidmaterial (e.g., an acrylic resin) to receive and retain the heater plateand tubing cassette thereon as described below. The base plate ispreferably transparent to enable viewing of intravenous fluid flowingwithin the cassette as described above. An upper portion 32 of the baseplate has dimensions greater than those of lower portion 31 to permitthe base plate to rest on the upper edges of the housing front, rear andside walls with the base plate lower portion slightly extending withinthe housing interior. An upper surface 34 of the base plate includes agenerally annular recess or groove 36 defined therein. The groovebasically forms a substantially circular engagement section 39 on thebase plate upper surface within an area defined by a groove innerdiameter or dimension. A channel 37 extends tangentially from acircumferential edge of the annular groove to a base plate front edge.Channel 37 includes an opening 75 for receiving a device temperatureprobe and a cassette temperature sensing fitting to measure temperatureof fluid within the cassette as described below. A serpentine channel 38including a generally ‘S’-shaped configuration is defined within section39 and facilitates proper alignment of cassette 50 within the device fortemperature heating and measurement of fluid as described below. Theends of channel 38 emerge from section 39 to communicate with annulargroove 36. A post 40 is disposed at the approximate center of channel 38and is typically constructed of an electrically conductive material(e.g., copper). The post facilitates formation of a conductive path toenable device operation as described below.

Heater plate 42 includes a configuration compatible with the uppersurface of base plate 30. Specifically, heater plate 42 includes agenerally annular portion 43 with an elongated and generally rectangularprojection 44 extending tangentially from an annular portioncircumferential edge. The heater plate is preferably flat, but mayinclude a grooved surface to receive cassette tubing sections or to formfluid flow paths to enable use of the device without the cassette.Channel projections 46 extend from the inner edge of the annular portionand are angularly spaced by approximately one-hundred eighty degrees.The channel projections are suitably configured and dimensioned tooccupy initial portions of channel 38 of base plate 30 while permittingconductive post 40 to be exposed. Heater plate 42 includes aconventional or other heating element 80 (FIG. 5) disposed on theunderside of the heater plate. The heating element is preferably in formof a conventional etched silicon rubber heating pad or other heateraffixed to the heater plate underside by a pressure sensitive adhesive.Alternatively, the heating element may be contoured to a heater plategrooved surface or be attached to the flat surface via any conventionalfastening techniques (e.g., adhesives, etc.). The heating element heatsthe heater plate and is coupled to a warming device control circuit tocontrol heating of the cassette as described below. Heater plate annularportion 43 and projections 44, 46 are disposed within groove 36 andchannels 37, 38 of the base plate, respectively, to enable the heaterplate to heat an engaging surface of a tubing cassette placed thereon.The heater plate may be constructed of any thermally conductivematerials.

Cassette 50 includes a configuration compatible with the base plate tofacilitate placement of the cassette within the warming device.Specifically, the cassette includes an inlet portion 52, an outletportion 54 adjacent the inlet portion and a cassette body 57 defining afluid flow path. The cassette body includes tubing sections 59,preferably transparent, arranged in generally circular and concentricsections 65, 67. A central serpentine tubing section 56 includes agenerally ‘S’-shaped configuration that basically reverses fluid flowand facilitates flow in opposing directions within adjacent concentrictubing sections 65, 67. In other words, fluid enters the cassette viainlet portion 52 and flows through concentric sections 65 toward centralserpentine tubing section 56. The serpentine section receives fluid froman innermost tubing section 65 and directs the fluid to flow inconcentric sections 67 toward outlet portion 54. Thus, fluid flows inconcentric sections 65 in a direction opposite to that of fluid flow inadjacent sections 67. The concentric tubing sections are in closeproximity to each other to enable thermal transfer between adjacentsections. The cassette may include any quantity of tubing sections toproduce a residence time within the warming device sufficient to heatthe fluid. The concentric tubing sections may be spaced a slightdistance from each other or be positioned to contact adjacent sections,while the tubing may be manipulated to form and maintain a cassetteconfiguration via any conventional techniques or manufacturing processes(e.g., molded, glued, etc.). The serpentine tubing section facilitatesalternate or opposing fluid flow directions (e.g., without utilizingoverlapping or serpentine type configurations) and proper alignment ofthe cassette within the base plate as described below. However, thecassette may include any configuration reversing fluid flow direction,and may include overlapping or non-overlapping tubing sections. Thecassette inlet, outlet and body may be constructed of a flexible plastic(e.g., polyvinyl chloride (PVC)) or any other material suitable for IVfluid line applications.

Inlet and outlet tubing portions 52, 54 are adjacent each other andextend tangentially from a circumferential edge of body 57. These tubingportions further include dimensions suitable for being received andretained within base plate channel 37. The inlet and outlet tubingportions terminate at respective inlet and outlet terminals 53, 55 thatextend externally of the device housing when the cassette is receivedand retained within the base plate annular groove and channels. Theinlet and outlet terminals include suitable connectors (e.g., Luerlocks) to connect inlet and outlet tubing portions 52, 54 to anyselected portions of an IV line. Serpentine tubing section 56 hasdimensions sufficient to be retained within base plate channel 38 andbasically facilitates appropriate alignment of the cassette within thebase plate for heating and temperature measurement of the fluid. Acontact 60 is disposed around a substantially central portion ofserpentine tubing section 56. The contact is preferably constructed ofan electrically conductive material (e.g., copper), and may be in anydesired form (e.g., a metallic band, wrap, rod, fluid, etc.). The baseplate configuration enables cassette contact 60 to contact conductivepost 40 and a contact 26 of cover heating element 25 when the tubingcassette is placed within the base plate groove and channels and thecover is in a closed state. The post and contacts basically serve toform or complete an electrical path or circuit to enable deviceoperation in response to proper placement of a compatible cassettewithin the device. The warming device may alternatively employ contactsor conductive members disposed on any device components at any locationsto form an electrical path through a pressure switch that senses closureof the device on the cassette for proper operation. The pressure switchmay further include a dual element sensor to measure fluid temperatureswithin the cassette inlet and outlet portions.

A sheet or backing 61 may be attached to the cassette top and/or bottomsurface to secure the tubing arrangement thereon. The sheet may includean annular configuration similar to that of cassette 50, and may includetabs 63 disposed on the sheet at any desired locations to facilitatemanipulation of the cassette relative to the warming device (e.g.,facilitate insertion and removal of the cassette within the warmingdevice). The warming device may accommodate any quantity of cassettes,while the cassette may include any quantity of preformed tubing to forma plural level or layer cassette. In other words, the cassette mayinclude any quantity of tubing sections disposed on any quantity ofplanes (e.g., stacked one above the other, etc.). This tends to provideadditional residence or heating time for fluid within the cassette. Thefluid flow path through the cassette may be formed in any manner, andmay be defined by any structures (e.g., tubing, sealed channels, pools,chambers, etc.).

Flow of IV fluid through cassette 50 is described. Basically, fluid froman IV line enters the cassette at inlet terminal 53 and is directed in awinding pattern through concentric tubing sections 65 toward serpentinesection 56. Upon reaching tubing section 56, the fluid is directed in anopposing direction through concentric tubing sections 67 toward outletportion 54 to exit the cassette at outlet terminal 55 and return to theIV line or be directed to a desired location (e.g., an infusion site).In essence, fluid flowing within the cassette travels in opposingdirections within adjacent concentric tubing sections of the cassettebody. The flow pattern defined by the tubing cassette provides a greaterresidence time for fluid within the cassette, thereby extending theexposure of the fluid to heating elements within the device housing.Further, the flow pattern enhances heat exchange between adjacent tubingsections 65, 67 that contain fluid exposed to the heating elements fordifferent intervals (e.g., fluid flowing within sections 67 towardoutlet portion 54 has a greater residence time than fluid flowing inadjacent tubing sections 65 toward serpentine section 56). It is to beunderstood that the designation of portion 52 as the inlet portion andportion 54 as the outlet portion is for illustrative purposes only,since either portion may serve as an inlet or outlet portion dependingupon the manner in which the terminals of the tubing cassette areconnected to an IV line.

Cover or lid 22 is generally rectangular and pivotally connected to anupper edge of rear wall 14 to selectively control access to the housing.The cover includes an open bottom portion and is configured to receiveand cover upper portion 32 of base plate 30. The cover may be connectedin any suitable manner to the housing rear wall via any fasteningdevices (e.g., hinges, brackets, etc.), and may include a handle (notshown) or any other suitable device or structure to facilitate pivotingof the cover with respect to the housing. The cover may alternatively beconnected to any of the housing walls or base plate, and may beconstructed of any suitable materials (e.g., an acrylic resin). However,the cover is preferably constructed of a transparent material to enableviewing of intravenous fluid flowing within the tubing cassette asdescribed above. A latching or locking mechanism (not shown) may bedisposed on the cover and/or housing to secure the cover in a closedstate and press the cover against the cassette to enhance contactbetween the cassette top and bottom surfaces and the cover heatingelement and heater plate, respectively.

The cover includes heating element 25 (FIG. 3) to apply heat to thecassette top surface. Specifically, heating element 25 is disposed on acover interior surface in facing relation with the heater plate. Theheating element is preferably implemented by a clear or transparentacrylic heater including a sheet 27 with electrically conductive wiring24 embedded therein. The transparent heating element enables viewing ofthe fluid flowing within the cassette as described above. Wiring 24 isarranged within sheet 27 and, hence, on the cover to coincide with thetubing cassette received on the base plate. The configuration of theelectrical wiring basically includes a generally annular body portion 29with a tangentially extending section 33. These sections basicallyoutline and are disposed coincident the corresponding body and inlet andoutlet portions of the cassette to apply heat to those cassettesections. Contact 26 (e.g., an electrically conductive plate) isdisposed on sheet 27 within the confines of wiring body portion 29 andfacilitates formation of an electrical path from the cover heatingelement contact through cassette contact 60 to the base plate conductivepost to enable device operation as described below. Wiring 24 furtherincludes connection terminals 28 disposed toward a circumferential edgeof wiring body portion 29 to connect the heating element to a devicecontrol circuit as described below.

In order to measure temperature of fluid within cassette 50, a fitting90 is disposed within outlet portion 54 at a location toward outletterminal 55. Fitting 90 (FIG. 4) includes a substantially cylindricalbase portion 92 and a generally cylindrical projection 94 extendingtransversely relative to the cassette tubing from an intermediatesection of the base portion. The base portion includes open ends 95 anda longitudinal channel defined therethrough to permit fluid flow throughthe base portion. The open ends are securable to outlet portion 54.Projection 94 similarly includes open ends and facilitates access to thebase portion channel. Fitting 90 typically includes a T-typeconfiguration, however, any configuration (e.g., a Y-type fitting, crossfitting, coupling, etc.) may be utilized. Each base portion open end 95may be secured to the outlet portion via any suitable connector, whilethe fitting is typically disposable with the cassette after each use tomaintain fluid sterility. The fitting may be constructed of plastic orany other rigid material suitable for use with IV lines. A thermallyconductive receptacle 96 is secured within projection 94 and extendspartially within base portion 92 for contacting fluid flowing within thebase portion channel. Receptacle 96 may be constructed of stainlesssteel or any other material having suitable thermal conductivity, andmay be secured within the projection via any suitable securingtechniques (e.g., friction fit, adhesives, etc.). The receptacleincludes a generally cylindrical body with a closed distal end thatextends partially within the base portion and an open proximal end forreceiving a temperature probe or sensor 98 as described below. A flangeextends radially from the open proximal end of the receptacle to engagean interior surface of the projection. The receptacle includesdimensions sufficient to provide a fluid tight seal between theprojection and base portion channel to maintain fluid within thechannel.

Temperature probe 98 is disposed within the device housing and extendsthrough opening 75 defined in the base plate to be removably insertedwithin the receptacle when the cassette is placed on the base plate. Thedistal end of the probe is disposed in contact with the receptacleclosed end, while the probe may be secured within the receptacle viafriction fit, a locking or securing mechanism or any other securingtechniques. Cassette 50 is placed on the heater plate with projection 94inserted within the base plate opening 75 to enable the probe to engagethe receptacle. Sensor wiring (not shown) connects the probe tocontroller 62 (FIG. 2) to provide a fluid temperature for controllingsystem operation. The receptacle is typically sterile and permits re-useof temperature probe 98 with subsequent cassettes to maintain sterility.The temperature probe may be implemented by any conventional or othertemperature sensor (e.g., RTD, IR, NTC, thermistor, thermocouple, etc.).The fitting may be substantially similar to the temperature sensingdevice disclosed in co-pending U.S. patent application Ser. No.09/______, entitled “Temperature Sensing Device for SelectivelyMeasuring Temperature at Desired Locations Along an Intravenous FluidLine” and filed on Oct. 11, 2001, the disclosure of which isincorporated herein by reference in its entirety.

Controller 62 (FIG. 2) has a generally rectangular configuration withsuitable dimensions to permit insertion of the controller into opening13 defined in the housing front wall. The controller includes a frontpanel 64 including dimensions slightly greater than opening 13 to allowthe front panel to remain external of the housing and accessible to auser. Front panel 64 includes a display 66 (e.g., LED, LCD, etc.) andinput devices 67 (e.g., buttons, keys, etc.) that enable entry of adesired or set point temperature for the fluid or other information(e.g., entering desired fluid heating temperatures, controls for variousthreshold heater plate temperatures, etc.) to direct controlleroperations. The set point temperature may alternatively be predeterminedor pre-programmed into the controller for device operation.

The controller display may provide various information to an operator(e.g., whether or not the tubing cassette is properly aligned on thebase plate to permit heating, utilization of an incompatible cassettewith the device, desired or set point temperature information,temperatures measured by temperature sensors disposed within the device,excessive temperature measurements, etc.). Alternatively, the housingmay include various visual and/or audible indicators (e.g., LED's,audio, speech, etc.) to indicate various conditions (e.g., properplacement of the cassette within the device, excessive temperatures,incompatible cassette being employed with the device, device ready foroperation, etc.). Further, the controller may provide variable controlsto control device operation in response to various temperaturemeasurements (e.g., output fluid temperature, cassette temperature,heating element temperatures, heater plate temperature and/orresistance, IV solution bag or container temperature, serpentine tubingsection temperature, etc.). The controller may further provide measuredtemperature information to an external display or a printer, and mayrecord the number of heating sessions conducted by the device byaccumulating the quantity of cover closures and/or heating elementenablements. The controller may provide this information, typically inthe form of a count, to the operator.

The cover and heater plate heating elements are controlled by thecontroller utilizing feedback from temperature sensors and/or probesdisposed within the housing in proximity to the heater plate and thetubing cassette. The controller basically provides resistive control ofthe heating elements disposed on the cover and heater plate (e.g.,adjusts power or current to these heating elements), and may controlthese heating elements based on a resistance measurement of the heaterplate, or based on the heater plate and/or fluid temperatures. Further,the warming device may include a plurality of sensors to monitor theheating elements, heater plate and/or cassette to provide varioussafeguards for device operation (e.g., disable the device in response toexcessive temperature measurements, etc.). The temperature sensors arepreferably implemented by conventional RTD temperature sensors, and arepreferably employed to measure the temperature of the heater plate andfluid flowing within the tubing cassette. However, the temperaturesensors maybe implemented by any conventional or other type oftemperature sensor (e.g., NTC, IR, thermocouple, thermistors, etc.) andmay measure any device component or fluid temperature. A heater platetemperature sensor 84 (FIG. 5) may be disposed at any suitable locationon or in close proximity to the heater plate for direct or indirecttemperature measurement. Similarly, a fluid temperature sensor may bedisposed at any suitable location on or within the tubing cassette fordirect or indirect temperature measurement of the fluid flowing therein.

An exemplary control circuit to facilitate control of device operationis illustrated in FIG. 5. Specifically, control circuit 70 includespower conductors 71, 72, a power switch 76, a solid state relay 78,heater plate heating element 80, cover heating element 25, a heatcontroller 82, heater plate temperature sensor 84, temperature probe 98and controller 62. The relay and heat control components (e.g., relay 78and controllers 62, 82) and corresponding electrical connections may behoused on a printed circuit board disposed within the device housing.Power conductors 71, 72 each include a respective fuse 73, 74 that isarranged in series with power switch 76 to prevent power surges fromdamaging the switch and circuitry. The conductors receive power from anexternal power source, preferably in the form of batteries. However, anysuitable internal or external power source may be utilized (e.g., AC,DC, wall outlet jack, batteries, etc.). Power may further be receivedfrom an infusion pump or device, such as the device disclosed in U.S.patent application Ser. No. 09/380,507, entitled “Method and Apparatusfor Pressure Infusion and Temperature Control of Infused Liquids” andfiled on Sep. 3, 1999, the disclosure of which is incorporated herein byreference in its entirety. Power switch 76 controls power to thecircuitry and is connected to controller 62, relay 78 and heatcontroller 82. The power switch may include a light 77 to illuminate theswitch. Controller 62 is further connected to relay 78 and temperaturesensors 84, 98, while heat controller 82 is further connected to relay78 and heating elements 25, 80. The heat controller controls power toboth heating elements to enable those elements to achieve and maintain apredetermined temperature (e.g., a temperature generally sightly greaterthan a desired fluid temperature). Controller 62 controls power to heatcontroller 82 , via relay 78, based upon a comparison of a preset ordesired temperature with temperatures of the heater plate and fluidwithin cassette 50 measured by temperature sensors 84, 98, respectively.In particular, controller 62 receives temperature signals from heaterplate temperature sensor 84 and temperature probe 98 indicating thetemperatures of the heater plate and IV fluid flowing within the tubingcassette. In response to either temperature measured by sensors 84, 98being equal to or exceeding the desired temperature, controller 62disables power to heat controller 82, thereby disabling heating elements25, 80. Conversely, when either of the temperatures measured by sensors84, 98 are below the desired temperature, controller 62 enables power tothe heat controller to energize those heating elements. Controller 62basically serves as a safety monitor to control device operation inresponse to fluid and/or heating element temperatures. Further,controller 62 may disable the heating elements in response to detectionof the absence of fluid within the cassette or detection of the presenceof air bubbles within the fluid. The fluid detection may be performed bya fluid sensor disposed within the warming device, or by temperatureprobe 98 providing a temperature measurement within a particular rangeor below a certain threshold. The air bubbles may be detected by anultrasonic air detector to enable cessation of fluid flow prior to airbubbles reaching a patient and causing injury.

Switches 86, 88 are connected in series between controller 62 and relay78. Switch 86 represents the connection between contact 60 (FIG. 2) oftubing cassette 50 with conductive post 40 of base plate 30 and contact26 of cover heating element 25, while switch 88 represents a switch toenable device operation when the cover is in a closed state. Theswitches basically permit relay 78 to be enabled by controller 62 inresponse to proper alignment of the tubing cassette on the base plate(e.g., the formation of the electrical path further serves to indicatethe presence of a cassette compatible with the warming device) andclosing of the cover. Thus, the switches enable device operation andcontrol of the cover and heater plate heating elements by controller 62during the presence of those conditions, and effectively disables theheating elements during absence of the conditions (e.g., the switchesdisable the heating elements in response to employment of anincompatible cassette, misalignment of the cassette on the base plate orthe cover residing in an open state).

Operation of the IV line temperature controlled warming device isdescribed with reference to FIGS. 1-5. Initially, an operator pivotscover 22 to an open position for insertion of IV tubing cassette 50between the base plate and the cover. The tubing cassette is insertedwithin the device with cassette body 57 aligned with annular groove 36,inlet and outlet portions 52, 54 and serpentine tubing section 56respectively aligned with channels 37, 38 and fitting projection 94disposed within base plate opening 75 to receive temperature probe 98within fitting projection receptacle 96. Upon proper insertion of thecassette into the warming device, contact member 60 contacts conductivepost 40 and contact 26 of the cover heating element to enable deviceoperation. The operator subsequently pivots the cover to a closedposition and secures the latching mechanism on the cover with thehousing to ensure contact between tubing cassette contact 60, conductivepost 40 and cover heating element contact 26. The controller mayindicate on display 66 proper securement of the tubing cassette withinthe base plate as described above, and may further indicate that theheating elements are enabled (i.e., switches 86, 88 are closed) to heatthe tubing cassette. Inlet and outlet terminals 53, 55 of the tubingcassette are connected to portions of an IV line that extends between anIV fluid supply source (e.g., an IV solution bag or container) to aninfusion site on a patient.

The operator may enter a desired temperature for the IV fluid flowingwithin the tubing cassette via the input devices on the controller frontpanel. Heat controller 82 controls the heating elements of the heaterplate and the cover to attain a predetermined temperature, whilecontroller 62 controls power to the heat controller, via relay 78, basedupon measured temperatures provided by the heater plate temperaturesensor and temperature probe. Thus, the warming device of the presentinvention enables fluid flowing within the tubing cassette to achieveand maintain a desired fluid temperature. The configuration of thecassette is also advantageous in that it provides a long residence timefor fluid flowing therein, thereby ensuring that fluid exiting thecassette attains the desired temperature. The concentric configurationof the tubing cassette portions further provides enhanced heat exchangebetween fluid within adjacent concentric tubing sections. Uponcompletion of a heating session, the cover may be opened, and the tubingcassette removed and discarded. A new and sterile tubing cassette maythen be inserted into the housing for use in another heatingapplication. The controller may further record the number of heatingsessions conducted with the warming device by counting the number oftimes the cover is closed (e.g., a tubing cassette is inserted withinthe housing and the cover is closed) and/or the heating elements areenabled. The controller may provide count information to the operatorrelating to the number of times the warming device has been utilized.

An exemplary pole type mount for use with the IV line warming device isillustrated in FIG. 6. Specifically, mount 100 includes an arm 103 and aswivel connector 102 (e.g., a manipulable bracket) securable around aportion of an IV pole 104 to attach the arm to the pole. Arm 103 issecured to connector 102 and includes a lower arm section 106 and anupper arm section 108. Each arm section includes a pair of generallycylindrical rods 105 extending substantially parallel to each other andsecured at each end to respective pivot mounts as described below. Lowerarm section 106 is pivotally secured at a proximal end to a proximalpivot mount or bracket 110 and at a distal end to an intermediate pivotmount or bracket 112. Proximal pivot mount 110 includes a substantiallycylindrical projection 122 that is received within a channel 124 definedin connector 102. The projection and channel rotatably secure proximalpivot mount 110 to connector 102, while a proximal helical spring 111 issecured at one end to proximal pivot mount 110 and at the other end to arod 105 of lower arm section 106. Upper arm section 108 is pivotallysecured at a proximal end to intermediate pivot mount 112 and at adistal end to a distal device mount or bracket 114. A base plate 116 isattached to the distal device mount, while a platform or tray 120 isattached to the base plate top surface to support an item, such as thewarming device. The tray may be manipulable relative to the distaldevice mount for enhanced positioning of an item. A distal helicalspring 113 is secured at one end to intermediate pivot mount 112 and atthe other end to a rod 105 of upper arm section 108. The connectionsbetween the rods and pivot mounts permit pivoting of the lower and upperarm sections relative to each other and to pole 104, therebyfacilitating placement of the warming device at a variety of locationswith respect to the IV pole.

It will be appreciated that the embodiments described above andillustrated in the figures represent only a few of the many ways ofimplementing a method and apparatus for heating solutions withinintravenous lines to desired temperatures during infusion.

The warming device may be of any shape or size, may be positioned at anydesired locations in any orientation, and may heat any types of medicalor other fluids. The device housing may be of any shape or size and maybe constructed of any suitable materials. The housing materials arepreferably transparent to enable viewing of the fluid and any conditionswithin the device (e.g., contamination, air bubbles, etc.), but may haveany degree of transparency (e.g., transparent, translucent, opaque,etc.). The housing walls may be of any quantity, shape or size and maybe constructed of any suitable materials. The controller may be disposedat any suitable location on or within the housing, while the housingopening may be of any shape or size and be defined at any suitablelocation on the housing to receive the controller. The housing interiormay include any suitable configuration to partially or completelyreceive any quantity of controllers, base plates, heater plates, IVtubing cassettes or other device components. For example, the housingmay be configured for receiving a plurality of tubing cassettes in orderto heat fluid within plural separate IV fluid lines. The devicecomponents may be arranged in any fashion within the housing.

The base plate may be of any quantity, shape or size, may include anysuitable configuration and may be constructed of any suitable materials.The base plate is preferably transparent to enable viewing of the fluidas described above, but may have any degree of transparency (e.g.,transparent, translucent, opaque, etc.). The base plate may be securedat any suitable location on or within the housing. The base plate lowerand upper portions may be of any quantity, shape or size, while the baseplate may be secured to the housing via any securing techniques (e.g.,friction fit, brackets, etc.). The base plate surface may include anyquantity of grooves and/or channels having any suitable configurationfor receiving and retaining the heater plate and cassette. The annulargroove and tangential channel may be of any shape or size and may bedefined at any suitable locations within the base plate. Alternatively,the base plate may include securing mechanisms (e.g., hooks, clasps,etc.) to secure the cassette to the base plate. The engagement sectionmay be of any quantity, shape or size and may be defined at any suitablelocations on the base plate. The serpentine channel may be of anyquantity, shape or size, and may be defined in the engagement section orbase plate at any suitable locations. The serpentine channel may includeany pattern or configuration (e.g., spiral, zig-zag, linear, etc.). Thetemperature probe opening may be of any quantity, shape or size, and maybe defined at any suitable locations within the base plate. Theconductive post may be of any quantity, shape or size, may be disposedat any suitable location within the serpentine channel or on the baseplate, and may be constructed of any suitable conductive materials.

The heater plate may be of any quantity, shape or size, and may beconstructed of any suitable thermally conductive materials. The heaterplate may include any suitable configuration for being received andretained by the base plate and for heating the tubing cassette. Theplate annular portion and projections may be of any shape or size, whilethe projections may be disposed at any suitable locations. The heaterplate may include a grooved or other type of surface to receive cassettetubing sections or to form fluid flow paths to enable use of the devicewithout the cassette. The heater plate may include any quantity of anytype of conventional or other heating element secured to the plate atany desired locations via any securing techniques (e.g., bracket,adhesives, etc.). The heater plate may include any quantity oftemperature or other sensors disposed at any suitable locations on orproximate the heater plate to measure heater plate temperature and/orresistance.

The tubing cassette may be of any quantity, shape or size and may beconstructed of any suitable materials. The cassette may include anysuitable configuration for being received and retained by the baseplate. The inlet and outlet tubing portions of the cassette may includeany suitable connector for securing those portions to any desiredsections of an IV line. The outlet portion may alternatively directheated fluid from the cassette to any desired location (e.g., aninfusion or other site, a storage container, etc.). The cassette mayinclude any type of tubing or other materials suitable to define a flowpath for fluid. The cassette may include any quantity of tubing sectionsarranged in any desired manner (e.g., concentric, serpentine, zig-zag,linear, spiral, etc.) to provide sufficient residence time for fluidwithin the device, wherein fluid flow directions within the sections maybe arranged in any desired pattern or fashion. The cassette may includeany quantity of concentric tubing sections, while the serpentine sectionmay include any configuration (e.g., serpentine, circular, linear,spiral, etc.) that reverses fluid flow within the cassette. Theserpentine section may be disposed at any location within the fluid flowpath. The warming device may accommodate any quantity of cassettes,while the cassette may include any quantity of tubing section layers(e.g., any quantity of tubing sections on any quantity of planes (e.g.,each stacked above or adjacent the other, etc.)). The cassette mayinclude any suitable structures to form the fluid flow path (e.g.,tubing, sealed channels, pools, chambers, etc.). The inlet and outletportions may be used in any fashion to enable fluid to flow into and outof the cassette.

The cassette backing may be of any quantity, shape or size, may receivethe cassette at any suitable locations, and may be constructed of anysuitable materials. The backing may include any configuration enablingaccess to the conductive post and contacts. The backing may include anyquantity of tabs of any shape or size and disposed at any suitablelocations. The tabs may be constructed of any suitable materials. Thecassette contact may be of any quantity, shape or size, may be disposedat any suitable locations on the serpentine section or cassette, and maybe constructed of any suitable conductive materials. The electrical pathmay be formed through any device components, where contacts may bedisposed on any quantity of any device components at any suitablelocations. The formation of the electrical path may be utilized toindicate any types of conditions (e.g., open cover, presence of fluid,placement of cassette, etc.). The electrical path may include a pressureswitch to sense closure of the cover, where the pressure switch mayinclude a dual sensor element to further sense temperature.

The housing cover may be of any quantity, shape or size, and may beconstructed of any suitable materials. The cover is preferabletransparent to enable viewing of the fluid as described above, but mayhave any degree of transparency (e.g., transparent, translucent, opaque,etc.). The cover may be secured to the housing or base plate in anymanner, and may include any quantity of any type of handle or otherstructure of any shape or size and disposed at any suitable location tofacilitate manipulation of the cover. The latching mechanism may be anytype of conventional or other securing device (e.g., hook and clasp,engaging members, etc.) for securing the cover to the housing and/orbase plate, and may be disposed at any suitable locations on thehousing, base plate and/or cover. The cover may include any quantity ofany type of conventional or other heating device (e.g., heating pad,acrylic heater, coils, etc.). The heating element wiring may be embeddedwithin or disposed on the sheet in any fashion and include anyconfiguration suitable to heat the cassette. The heating element contactmay be of any quantity, shape or size, may be disposed within or on thesheet at any suitable locations and may be constructed of any conductivematerials. The terminals maybe of any quantity, shape or size, and maybeembedded within or disposed on the sheet at any suitable locations.

The fitting may be of any quantity, shape or size, may be constructed ofany suitable materials and may be disposed at any suitable locationsalong the IV line or cassette. The fitting base and projection maybe ofany quantity, shape or size and maybe constructed of any suitablematerials. The base channel may be of any shape or size, may be definedin the base at any locations and extend in any desired directions. Thefluid line or cassette may be secured to the fitting via anyconventional or other locks or connectors. The base and projection maybe arranged or connected in any fashion, while the fitting may have anysuitable configuration (e.g., T-type fitting, Y-type fitting, crossfitting, coupling, etc.). The fitting may be included within andpermanently or releasably connected to the cassette or a disposable IVline set. The fitting may include a receptacle to maintain fluidsterility and permit re-use of the temperature probe. The receptacle maybe of any quantity, shape or size, may be constructed of any suitablythermally conductive materials and may be disposed at any locationswithin the projection or fitting suitable to contact or thermallyconduct heat from fluid flowing within the fitting. The receptacle bodyand flange may be of any quantity, shape or size and may be constructedof any suitable materials. The temperature probe maybe inserted andsecured within the base plate opening and receptacle via anyconventional or other securing techniques (e.g., friction fit, threadedengagement, securing mechanism, etc.). Similarly, the receptacle may besecured within the projection or fitting via any conventional or othersecuring techniques (e.g., friction fit, adhesives, threaded engagement,securing mechanism, etc.). The fitting may alternatively include thetemperature probe embedded therein.

The temperature sensors or probes of the warming device maybe of anyquantity and may be disposed at any suitable locations within or on thedevice or device components (e.g., base plate, heater plate, cassette,housing, etc.) to measure any desired temperatures. The temperaturesensors or probes may be implemented by any quantity of any type ofconventional or other temperature measuring devices (e.g., RTD, IR, NTC,thermistors, thermocouples, etc.). The sensors or probes may be of anyshape or size to accommodate a particular application.

The controller may be implemented by any quantity of any conventional orother microprocessor, controller or circuitry. The controller may bedisposed at any suitable location on or within the housing or separatefrom the device (e.g., wireless or other communication link tocomponents, etc.). The controller may include any quantity of any typeof display (e.g., LED, LCD, etc.) or indicators (e.g., visual, audio,speech synthesis, etc.) disposed at any suitable locations to convey anydesired information or conditions to an operator (e.g., desiredtemperatures, measured temperatures, improper placement of cassettewithin device, etc.). The controller may include any quantity of anytype of input devices (e.g., buttons, keys, voice recognition, etc.) toreceive information.

The fluid temperature may be predetermined or entered by a user, wherethe device typically heats fluid to temperatures in the approximaterange of 60° F.-160° F. However, the device may be utilized to heatand/or cool fluid (e.g., by employing cooling or refrigeration devicesinstead of or in conjunction with the heating elements) to any desiredtemperature or temperature range. The controller may be coupled to anyquantity of external displays or printing devices to display and/orprint any desired information. The controller may further control deviceoperation in response to any measured conditions (e.g., fluid flow,various temperatures, contamination, air bubbles, etc.). The warmingdevice may employ any quantity of any type of sensors (e.g., flowsensors, fluid sensors to detect fluid, temperature sensors, resistivesensors, ultrasonic air detectors or other sensors to detect airbubbles, etc.) to measure and/or detect conditions to control deviceoperation.

The controller may record and facilitate display of device utilizationinformation (e.g., the amount of time of device use, quantity of timesthe cover has been closed, the quantity of times of heater enablement,etc.). The controller may receive any quantity of inputs and control anyquantity of warming devices, and may utilize any conventional or othercontrol algorithms (e.g., fuzzy logic, PID, etc.).

The heat controller may be implemented by any quantity of anyconventional or other microprocessor, controller or circuitry. The heatcontroller may control the heating elements to any desired temperatureor temperature range, but preferably controls the heating elements totemperatures slightly above the desired range for the application. Theheat controller may receive any quantity of inputs and control anyquantity of heating elements, and may utilize any conventional or othercontrol algorithms (e.g., fuzzy logic, PID, etc.). The device may employthe controller to directly control the heating elements without the heatcontroller. The controllers are each typically implemented by acommercially available controller pre-programmed and loaded with its ownsoftware, but may be implemented by any quantity of any conventional orother type of controller, microprocessor, or circuitry capable ofcontrolling the warming device.

The control circuit components (e.g., power switch, relay, fuses,controllers, etc.) may be implemented by any quantity of anyconventional or other electrical components arranged in any fashion andperforming the functions described above. The circuit may be disposed atany location on the or within the housing and may be arranged in anyfashion to control device operation as described above. The fuses may beimplemented by any conventional or other fuses or limiting devicesconfigured for any desired current level. The power switch andcontrollers may be disposed at any suitable locations on or within thehousings. The printed circuit board may include any quantity of anycircuit components, while the control circuit may receive power from anysuitable power source (e.g., AC, DC, wall outlet jack, batteries,infusion device, etc.). The control circuit may be modified in anyfashion and include any components to perform the functions describedherein. The switches may be implemented by any conventional or otherswitching devices to enable or disable device operation in response toany desired conditions.

The warming device may be supported in various positions andorientations by any suitable structures (e.g., a patient arm or otherbody portion, swing arm, arm board, bed, bed rail, operating room orother table, IV pole, wall, floor, posts, etc.). The warming device ispreferably positioned in close proximity to an infusion site of apatient in order to heat IV fluid (e.g., may heat fluid with or withoutskin contact), but may be used at any desired location along an IV line.The warming device may be utilized for operating room, pre-op and/orpost-op procedures or at any other times where infusion is beingperformed. The mount may be of any shape or size, and may be constructedof any suitable materials. An IV pole or other structure may support anyquantity of mounts and/or warming devices. The mount components (e.g.,pivot mount, connectors, springs, rods, base plate, tray, etc.) may beof any quantity, shape or size, may be constructed of any suitablematerials and may be disposed or connected at any suitable locations inany desired orientation or manner relative to each other (e.g., the rodsmaybe parallel to each other or arranged in any fashion, the tray may beconnected to the base plate at any location, etc.). The components maybe connected via any suitable securing techniques (e.g., bolts,integrated, hooks, etc.), and may be arranged and/or connected to eachother in any fashion. Further, the mount components may be implementedby any conventional or other components performing the functionsdescribed herein. The projection may be of any quantity, shape or size,while the channel may be of any quantity, shape or size and defined inthe connector at any suitable location. The arm may alternatively beconnected to the connector via any conventional or other securingtechniques (e.g., bracket, hinge, etc.).

From the foregoing description, it will be appreciated that theinvention makes available a novel method and apparatus for heatingsolutions within intravenous lines to desired temperatures duringinfusion, wherein a warming device receives and heats a preformed IVtubing cassette or cartridge connected to an IV line to warm solutionflowing within the line to a desired temperature during infusion into apatient.

Having described preferred embodiments of a new and improved method andapparatus for heating solutions within intravenous lines to desiredtemperatures during infusion, it is believed that other modifications,variations and changes will be suggested to those skilled in the art inview of the teachings set forth herein. It is therefore to be understoodthat all such variations, modifications and changes are believed to fallwithin the scope of the present invention as defined by the appendedclaims.

1. A warming device for heating intravenous fluids to desiredtemperatures comprising: a housing; a fluid cassette removably securablewithin said device to receive fluid from an intravenous fluid line,wherein said fluid cassette includes fluid line tubing arranged to forma fluid flow path through said cassette; a plurality of heating elementsdisposed within said housing to heat said fluid cassette, wherein saidheating elements are positioned to facilitate insertion of said cassettebetween at least two heating elements; at least one temperature sensorto measure at least one temperature within said housing; and acontroller coupled to said at least one temperature sensor and saidheating elements to control said heating elements in accordance withsaid at least one measured temperature.
 2. The warming device of claim1, wherein said controller further enables said heating elements whensaid fluid cassette is secured within said device and disables saidheating elements when said fluid cassette is absent from said device. 3.The warming device of claim 1, wherein said housing further includes: acover including at least one of said heating elements to heat said fluidcassette; a heater plate including at least one of said heating elementsto receive and heat said fluid cassette; and a base plate including areceiving surface to receive and retain said heater plate and said fluidcassette within said device.
 4. The warming device of claim 3, wherein:said base plate further includes an electrically conductive postdisposed on said receiving surface; said fluid cassette further includesan electrically conductive contact disposed around a portion of saidfluid line tubing; each said cover heating element includes a contactplate; and said controller controls said heating elements in response tosaid contact engaging said conductive post and said contact plate. 5.The warming device of claim 1, wherein said fluid cassette includesinlet and outlet terminals disposed proximate each other.
 6. The warmingdevice of claim 5, wherein said fluid cassette tubing includes an inlettubing section including said inlet terminal and an outlet tubingsection including said outlet terminal, and wherein said fluid cassetteincludes tubing sections extending adjacent each other in a spiralconfiguration to form an annular section of said tubing cassette withsaid inlet and outlet tubing sections extending tangentially from saidannular section.
 7. The warming device of claim 6, wherein said annularsection includes an intermediate section to direct fluid flow receivedfrom said inlet terminal in a reverse direction through said annularsection tubing sections toward said outlet terminal.
 8. The warmingdevice of claim 1, wherein said intravenous fluid line is connected to apre-heated container of fluid and said device is positioned toward apatient infusion site, and wherein said controller controls said heatingelements to heat said fluid to compensate for heat loss due to exposureof said intravenous line fluid to an ambient environment duringinfusion.
 9. The warming device of claim 1, wherein said fluid cassettetubing includes concentric tubing sections each defining a path forfluid flow in a particular direction, and wherein said fluid flowdirection within each concentric tubing section is opposite to the fluidflow direction within a concentric tubing section adjacent that section.10. The warming device of claim 1, wherein said fluid cassette includesa fitting in fluid communication with said fluid line tubing to measuretemperature of fluid flowing within said fluid cassette.
 11. The warmingdevice of claim 10, wherein said fitting includes a thermally conductivemember in direct contact with fluid flowing within said fitting, andsaid housing further includes: a temperature sensing probe suitablydimensioned to extend within said fitting and releasably engage saidthermally conductive member to measure temperature of said fluid flowingwithin said cassette.
 12. The warming device of claim 1, wherein saidcontroller selectively enables and disables said heating elements inaccordance with a comparison of said at least one measured temperaturewith a desired fluid temperature.
 13. The warming device of claim 12,wherein said controller includes at least one input device to facilitateentry of said desired fluid temperature.
 14. The warming device of claim1, wherein said housing further includes a heater plate including atleast one of said heating elements to receive and heat said fluidcassette, wherein said at least one temperature sensor includes a firstsensor disposed proximate said heater plate to measure a temperature ofsaid heater plate and a second sensor disposed proximate said fluidcassette to measure a temperature of fluid flowing therein, and whereinsaid controller selectively enables and disables said heating elementsin accordance with a comparison of said measured temperatures with adesired fluid temperature.
 15. The warming device of claim 1 furtherincluding a heat controller to control said heating elements to attain apredetermined temperature, wherein said heat controller is selectivelydisabled by said controller in accordance with said at least onemeasured temperature.
 16. The warming device of claim 1 furtherincluding a pivotable mount securable to a support structure to receiveand place said warming device in a desired position. 17-23. (canceled)24. In a warming device including a housing, a fluid cassette removablysecurable within said warming device, a plurality of heating elements,at least one temperature sensor and a controller, a method of heatingintravenous fluids to desired temperatures comprising the steps of: (a)receiving fluid within said cassette from an intravenous fluid line,wherein said fluid cassette is disposed within said warming devicebetween at least two of said heating elements and includes fluid linetubing arranged to form a fluid flow path through said cassette; (b)heating said fluid cassette within said warming device via said heatingelements; (c) measuring at least one temperature within said housing;and (d) controlling said heating elements in accordance with said atleast one measured temperature.
 25. The method of claim 24, wherein step(d) further includes: (d.1) enabling said heating elements when saidfluid cassette is secured within said device and disabling said heatingelements when said fluid cassette is absent from said device.
 26. Themethod of claim 24, wherein said housing further includes a coverincluding at least one of said heating elements, a heater plateincluding at least one of said heating elements to receive and heat saidfluid cassette and a base plate including a receiving surface to receiveand retain said heater plate and said fluid cassette within said device,and step (d) further includes: (d.1) controlling said cover and heaterplate heating elements in accordance with said at least one measuredtemperature to heat said fluid cassette.
 27. The method of claim 26,wherein said base plate further includes an electrically conductive postdisposed on said receiving surface and said fluid cassette furtherincludes an electrically conductive contact disposed around a portion ofsaid fluid line tubing, wherein each said cover heating element includesa contact plate, and step (d.1) further includes: d.1.1) controllingsaid heating elements in response to said contact engaging saidconductive post and said contact plate.
 28. The method of claim 24,wherein said fluid cassette includes inlet and outlet terminals disposedproximate each other, and step (a) further includes: (a.1) receivingfluid from said intravenous fluid line via said inlet terminal; and step(d) further includes: (d.1) directing heated fluid from said fluidcassette to said intravenous line via said outlet terminal.
 29. Themethod of claim 28, wherein said fluid cassette tubing includes an inlettubing section including said inlet terminal and an outlet tubingsection including said outlet terminal, wherein said fluid cassetteincludes tubing sections extending adjacent each other in a spiralconfiguration to form an annular section of said tubing cassette withsaid inlet and outlet tubing sections extending tangentially from saidannular section, wherein said annular section includes an intermediatesection, and step (a.1) further includes: a.1.1) directing fluid flowreceived from said inlet terminal in a reverse direction through saidannular section tubing sections toward said outlet terminal via saidintermediate section.
 30. The method of claim 24, wherein saidintravenous fluid line is connected to a pre-heated container of fluidand said device is positioned toward a patient infusion site, and step(d) further includes: (d.1) controlling said heating elements to heatsaid fluid to compensate for heat loss due to exposure of saidintravenous line fluid to an ambient environment during infusion. 31.The method of claim 24, wherein said fluid cassette tubing includesconcentric tubing sections each defining a path for fluid flow in aparticular direction, and step (a) further includes: (a.1) directingfluid flow in a direction within each concentric tubing section that isopposite to the fluid flow direction within a concentric tubing sectionadjacent that section.
 32. The method of claim 24, wherein said fluidcassette includes a fitting in fluid communication with said fluid linetubing, and step (c) further includes: c.1.) measuring temperature offluid flowing within said fluid cassette via said fitting.
 33. Themethod of claim 32, wherein said fitting includes a thermally conductivemember in direct contact with fluid flowing within said fitting and saidhousing further includes a temperature sensing probe suitablydimensioned to extend within said fitting and releasably engage saidthermally conductive member, and step c.1.) further includes: c.1.1)measuring temperature of said fluid flowing within said cassette viasaid temperature sensing probe.
 34. The method of claim 24, wherein step(d) further includes: (d.1) selectively enabling and disabling saidheating elements in accordance with a comparison of said at least onemeasured temperature with a desired fluid temperature.
 35. The method ofclaim 34, wherein said controller includes at least one input device,and step (d.1) further includes: d.1.1) facilitating entry of saiddesired fluid temperature via said at least one input device.
 36. Themethod of claim 24, wherein said housing further includes a heater plateincluding at least one of said heating elements to receive and heat saidfluid cassette, wherein said at least one temperature sensor includes afirst sensor disposed proximate said heater plate and a second sensordisposed proximate said fluid cassette, and step (c) further includes:c.1.) measuring a temperature of said heater plate via said firstsensor; and (c.2) measuring a temperature of fluid flowing within saidfluid cassette via said second sensor; and step (d) further includes:(d.1) selectively enabling and disabling said heating elements inaccordance with a comparison of said measured temperatures with adesired fluid temperature.
 37. The method of claim 24, wherein saidwarming device further includes a heat controller, and step (d) furtherincludes: (d.1) controlling said heating elements to attain apredetermined temperature via said heat controller, wherein said heatcontroller is selectively disabled by said controller in accordance withsaid at least one measured temperature.
 38. The method of claim 24,wherein said warming device further includes a pivotable mount securableto a support structure, and step (a) further includes: (a.1) receivingsaid warming device on said mount to facilitate placement of saidwarming device in a desired position.
 39. A warming device for heatingintravenous fluids to desired temperatures comprising: a housing; fluidflow means removably securable within said device for receiving fluidfrom an intravenous fluid line, wherein said fluid flow means includesfluid line tubing arranged to form a fluid flow path through said fluidflow means; a plurality of thermal means disposed within said housingfor heating said fluid flow means, wherein said thermal means arepositioned to facilitate insertion of said fluid flow means between atleast two thermal means; temperature means for measuring at least onetemperature within said housing; and control means coupled to saidtemperature means and said thermal means for controlling said thermalmeans in accordance with said at least one measured temperature.
 40. Thewarming device of claim 39, wherein said control means includesdetection means for enabling said thermal means when said fluid flowmeans is secured within said device and disabling said thermal meanswhen said fluid flow means is absent from said device.
 41. The warmingdevice of claim 39, wherein said housing further includes: a coverincluding at least one of said thermal means to heat said fluidcassette; heat applying means including at least one of said thermalmeans for receiving and heating said fluid flow means; and base meansincluding a receiving surface for receiving and retaining said heatapplying means and said fluid flow means within said device.
 42. Thewarming device of claim 41, wherein: said base means further includes anelectrically conductive post disposed on said receiving surface; saidfluid flow means further includes an electrically conductive contactdisposed around a portion of said fluid line tubing; each said coverthermal means includes a contact plate; and said control means includesdetection means for controlling said thermal means in response to saidcontact engaging said conductive post and said contact plate.
 43. Thewarming device of claim 39, wherein said fluid cassette includes inletand outlet terminals disposed proximate each other.
 44. The warmingdevice of claim 43, wherein said fluid flow means tubing includes aninlet tubing section including said inlet terminal and an outlet tubingsection including said outlet terminal, wherein said fluid flow meansincludes tubing sections extending adjacent each other in a spiralconfiguration to form an annular section of said fluid flow means withsaid inlet and outlet tubing sections extending tangentially from saidannular section.
 45. The warming device of claim 44, wherein saidannular section includes an intermediate section to direct fluid flowreceived from said inlet terminal in a reverse direction through saidannular section tubing sections toward said outlet terminal.
 46. Thewarming device of claim 39, wherein said fluid flow means tubingincludes concentric tubing sections each defining a path for fluid flowin a particular direction, and wherein said fluid flow direction withineach concentric tubing section is opposite to the fluid flow directionwithin a concentric tubing section adjacent that section.
 47. Thewarming device of claim 39, wherein said fluid flow means includes afitting in fluid communication with said fluid line tubing to measuretemperature of fluid flowing within said fluid flow means.
 48. Thewarming device of claim 39, wherein said control means includes powermeans for selectively enabling and disabling said heating elements inaccordance with a comparison of said at least one measured temperaturewith a desired fluid temperature.
 49. The warming device of claim 39,wherein said housing further includes a heat applying means including atleast one of said thermal means for receiving and heating said fluidflow means, wherein said temperature means includes first sensing meansdisposed proximate said heat applying means for measuring a temperatureof said heat applying means and second sensing means disposed proximatesaid fluid flowing means for measuring a temperature of fluid flowingtherein, and wherein said control means includes power means forselectively enabling and disabling said thermal means in accordance witha comparison of said measured temperatures with a desired fluidtemperature.
 50. The warming device of claim 39 further including heatcontrol means for controlling said thermal means to attain apredetermined temperature, wherein said heat control means isselectively disabled by said control means in accordance with said atleast one measured temperature. 51-62. (canceled)